/Engine/Source/Runtime/Engine/Classes/Animation/AnimCompress_RemoveLinearKeys.h
If the passed in animation sequence is additive, converts it to absolute (using the frame 0 pose) and returns true (indicating it should be converted back to relative later with ConvertToRelativeSpace)
void ConvertFromRelativeSpace ( [FCompressibleAnimData](API\Runtime\Engine\Animation\FCompressibleAnimData) & CompressibleAnimData )